Coffee mill



G. R. WOOD April 17, 1951 COFFEE MILL 2 Sheets-Sheet 1 Filed April 11, 1946 INVENTORU O m 6 v 0 Paw 2 Sheets-Sheet 2 INVENTOR. Geo/"7e 14?. H600 BY ATTORNEYS G. R. WOOD COFFEE MILL v A x [Earl 115.....J1lll121lll441l 52.542: 555:-- 1-..

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Patented Apr. 17, 1951 COFFEE MILL George Rue Wood, Toledo, Ohio, assignor to Toledo Scale Company, Toledo, Ohio, at corpora tion of New Jersey Application April 11, 1946, Serial No. 661,441

Claims. (Cl. 241---246) This invention relates to coffee mills and in particular to improvements in the burr adjusting mechanism which regulates the fineness of the grinding.

. be accurately regulated. In many coffee grinding machines the rotating burr is carried directly on the motor shaft and means are provided for moving the stationary burr toward or away from the rotating burr for adjusting the clearance between them. This arrangement suffers from the disadvantage that the axial thrust of the burrs must be carried by the motor shaft bearings and that the motor bearings are subject to very high axial loads in case hard foreign material gets between the burrs. Besides these operating difliculties the conventional mechanisms for adjusting the clearance between the burrs by moving the stationary burr are usually complicated and expensive.

The principal object of this invention is to provide a cofiee mill in which none of the axial thrust produced by the grinding burr is carried by the motor shaft.

Another object is to provide a coffee grinder in which the stationary burr is rigidly mounted from the cover of the burr chamber and the rotating burr is axially adjusted by a burr supporting and adjusting means extending through a tubular motor shaft.

Another object is to provide a vertically disposed coffee mill with grind selecting mechanism located in the base of the mill.

A still further object is to provide a coffee mill constructed so that the mill may be disassembled for cleaning and reassembly with complete assurance that the adjustment of the clearance between the burrs will not be detrimentally affected.

These and other objects and advantages are apparent from the following detailed description of a specific embodiment of the invention.

According to the invention the motor shaft is relieved of axial thrust and the clearance between the burrs is regulated by slidably keying the rotating grinding burr to a tubular motor shaft, supporting the rotating burr on the end of an adjusting rod passed axially through the tubular motor shaft and positioning the rod axially with respect to the motor shaft by a cam-supported thrust bearing located between the rod and the base on which the motor is mounted. This arrangement separates the adjusting means from the burr chamber so that the adjusting means is not exposed to the dust and chaff which is inevitably present when coffee is being ground. Furthermore, it permits the burrs to be positively and rigidly held with proper clearance maintained between them.

A specific embodiment of the invention is illustrated in the accompanying drawings, in which:

Figure I is a vertical section of a coffee mill embodying the invention.

Figure II is a fragmentary plan view looking down into the grinding chamber, parts being shown in section and parts broken away to reveal the details of construction.

Figure III is a fragmentary plan view, partly in section, taken substantially along the line III III of Figure I.

Figure IV is a fragmentary vertical section at an enlarged scale, the section being'taken substantially along the line IV-IV of Figure I.

Figure V is a plan view taken substantially along the line V-V of Figure IV, the removable part of the cam having been removed to show the camming surfaces of the stationary cam.

These specific figures and the accompanying description are intended merely to illustrate the invention but not to impose limitations on the claims.

The coffee mill selected to illustrate the invention has a driving motor I whose lower end frame 2 is provided with legs 3 terminating in feet 4 which by means of bolts 5 are secured to a shelf 6 of a generally cylindrical base I. If desired, a ring of resilient material may be installed beneath the side wall of the base I to prevent it from marring a counter top or other surface on which the coifee mill is placed.

An upper end bell or frame 8 of the motor I is extended upwardly to form a cup-shaped grinding chamber 9. The motor I and the grinding chamber 9 are surrounded by a generally cylindrical housing ID. The housing I0, made of thin sheet metal or similar material, rests in a groove II cut in the top of the side walls of the base I and fits into a groove I2 in the under surface of a housing ring I3. Thehousing ring I 3 has several inwardly directed arms I4 which by means of bolts I5 are secured to a'flange I6 extending laterally from the grinding chamber 9. A cylindrical hopper support I! which is set into the housing ring l3 extends upwardly and is terminated in an inwardly directed ledge I8 defininga large circular hole in the top of the housing. A hopper 19 having a shouldered supporting ring 20 secured at its upper edge fits into the hopper support I! with one of the shoulders of the supporting ring 20 resting on the ledge l8. The hopper is provided with a domed cover 2| hinged along one side of the hopper. Immediately below the hinge a bafileplate 22 is fitted within the hopperl9rso that an edgej23" of the cover 21 behind the hinge may swing down and by contacting the baffle plate 22 limit the travel of :the

cover 2|. The baffie plate 22 also prevents any coffee beans from lodging beneath the hinge where they would interfere withthe opening or closing of the cover 2 l. 1

chamber 9 has radially extending'ears'25 adapted 4 y the motor shaft. Immediately below the level of the rotating table the motor shaft 33 is pro vided with a broached hole 4| through which a flat key 42 is fitted. The hub 31 of the rotating table 38 rests on the ends of the key 42 which in turn is supported on an adjustingrod 43 extending axially through the tubular motor shaft 33. Axial adjustment of the adjusting rod 43 regulates the clearance between the burrs 28 and 29 and thus controls the. fineness of the grind.

lhe rotating table 38 carrying the lower burr 29 has a number of vanes 44 erected in the space ;radially outside of the burr 29. The vanes 44 serve to sweep the ground coffee around the periphery of the grinding chamber 9 and to force it out-through a generally tangential discharge ;.-.passag e 45.-,which terminates in a downwardly to lock beneath catches 26 screwed toithe upper surface of the flanges I6. A pair of wings 21, similar to the wings of a wing nut,..extend .upwardly from the c'over124 sothat it maybe rotated ;byhand.when it isnecessaryto remove it to clean or inspect the. machine.

. The cover 24 has an axial opening'through it which registers with the bottom end of the hopper l9.so that materialplacedin the hopper. maybe fed into thegrinding chamber 9. A stationary annular grinding burr. 28 is securedto the lower surface ofwthe cover .24. and is thus rigidlypositioned with respect to the grinding chamber 9.

rotatingrburr=29 adapted to cooperate with the'stationary burr 28 is mounted on arotating table-38, which is a closfitwithiri the chamber 9. The rotatingltableuiin. has a hub portion 31' .extendingdownward andanother hub portion- 32 extending upwardly to hold it on a tubular motor shaft 33,extending-upwardly into the grinding chamber 9. The tubular motor shaft33 isv carried in a sleeve bearing 34 at its-lower .end'and win a ball bearing. 35 located in the end frame 8.

The upper end of the armature shaft 33 is slotted and one. sidefof theupwardly extending hub 32 of vtherotatingfltable'. 39 issimilarly slotted so that'a disk-"39 similar in-size'a'nd shape to a I coppericent maybe employed as a shearable key to transmit torque from the motor, shaft 33 to the rotating table 130. .The disk 36 is heldin position inlthe .slotsby acap31 fitted .down over.

. catch, as-happens when a piece-of foreign material gets between the burrs; the disk .36 is sheared and themotor can. continue to rotate.

, When this occurs the machine may be easily disassembled by removingzthe hopperand the grinding chamber cover 24 which exposes the lower burr so that the foreign material maybe removed.

Thecap 3'! may then be removed to expose the .disk 36 sothat it maybe pushed out of the slots in the end of the. motorshaft and, the hub 32 andeitherreplaced by a new disk or turned part way around so that anew portion is engaged between the shaft'and the hub. The cap 31, the cover 24 and the hopper I 9 may then be replaced.

A plug 40 driven into the tubular motor shaft 33 until its top is immediately below the bottom of the slotsin the end of the shaft prevent any sheared pieces of the disk 3.6irom droppingdown .rotating table 39.

directed spout 48. The passage opens into the grinding chamber 9 at such an elevation that its lower surface is slightly below the to of the This arrangement of parts combined with the close fit between the peripherylofthe,rotatingtable 39 and the .interior of the. grinding chamber ,9 effectively prevents leakage of ground c'ofie'e into thejspace beneaththe riedin a special thrust bearingwhich permits its axial position with respect to the grinding chamber 9sto be accuratelyregulated..Thisflthrust bearing comprises a stationary cam 41' whose ..flanged base'48 is screwed to the shelf fiof the base i. The active surface 'Of l'IhG CaIfi HJ consists"ofthree 120 helical sections"49. Acupsupported rim down "on'the" stationary cam :41

with the two sets of helicalsurfaces in contact 'with each other.

cup-shaped cani'followerifl andis securedin place by a. nut53 screwedonto the stud 52 above the cam follower58."The' stud 52 extends} down through a'hole54' drilledthrough the center of the'stationary. cam 41 so" that the studf52may serveas a pilot to. maintain the cam follower in axial alignment with -thecani 41 as it. is roi tated thereon. A shallow'slot isrnilled across the top surface" of the'cam followe'r158 toreceive ahandle. 55 formedvof a strip of heavysheet sothat it may be. easily moved side-waystorotate the cam follower 59 with respect. to the station- 7 ary cam 41.

L The stud. 52 set in the cam follower Ellis bored out to journalthe lower end of the" adjusting rod =43- Frictionbetween the end of the rod 43.and

..the stationary parts; of. the bearing is-minimized ,gby a hardenedsteel bearingball dropped-into the hollowed-out, stud 5 2 beforethe rod43 put 1 in place. The lower end. oftthe rod -4.3salso.may be hardened to reduce wear.- The-bearing ball 51 rests on the .upperend of, anadjustingscrew 58 threaded axially-upwardly through-thebottom lend of thestud152.. It is.:locked;-inits adjusted .positionby-alock nut. 59.

, .the coffee mill to adjustthe screw 58 ofthe-thrust bearing to compensate for. wear ofthe burrs.

. In this. arrangement the --burrs gare adjusted grinding I for fine, medium or coarse grind by manipula- ..tion of the handle 55 which. rotates thecam follower with respect to the cam and thus raises or lowers the adjusting rod 43 .with respect to .the The adjustment provided To. hold the handle 55in its selectedposition a detent plate BI is welded or otherwise secured to thehandle i 55 adjacent the cam follower 50.

The ,detent plate 6! is provided with aplurality of notches 62 and stops '63 which cooperate with a detent assembly 54 consisting of a block 65 screwed to the shelf 6 and having a drilled hole 66 to accommodate a ball 6'! and a spring 63. The hole 66 is in horizontal alignment with the detent plate 61 and is placed so that the spring pressed ball 68 may engage the notches 62 and thus establish definite positions for the handle 55 and cam follower 50. 7

If desired, suitable indicia may be inscribed on the wall of the base 1 adjacent the path of the handle 55. These indicia serve to mark the positions of the handle 55 required to secure various grinds of coffee, such as coarse, medium, fine, etc. The number of degrees of fineness for which the cofiee mill may be positively adjusted is determined by the numbe of notches 62 provided in the detent plate 6|.

While the handle 55 has been shown extending from a side of the housing its location may easily be changed so as to bring it out at the front or some other convenient position.

In the improved coffee mill design as shown in the example the thrust of the grinding burrs in the burr chamber 9 is carried by the adjusting rod 43 and the thrust bearing mounted on the shelf 6 so that no axial thrust is transmitted to the motor bearings. burrs is very easily adjusted by a conveniently located handle and the adjustment is not altered in any Way when the burrs are disassembled for cleaning Or to remove foreign material. The only place in which dust or coffee chaff could possibly affect the burr clearance is between the rim of the burr chamber and the cover. But in that event it would be found exceedingly difiicult or impossible to engage the ears 25 beneath the locking lugs 26 secured to the flange of the burr chamber. All the adjustments for the grinder may be easily made from the exterior of the machine and are not disturbed during normal cleaning operations.

Various modifications or substitutions can be made without losing the advantages afforded by the improved design. Therefore the specific example described should be considered as illustrative only and not as defining the scope of the invention.

Having described my invention, I claim:

1. In a device of the class described, in combination, a base, a motor mounted on end on the base, end frames for the motor the lower one of which serves to support the motor from the base, a burr chamber formed integrally with the upper end frame of the motor, an apertured cover for the chamber, means for feeding material into and from the chamber, a burr non-adjustably attached to the cover, a tubular shaft for the motor, a rotatable burr driven by and slidable along the tubular shaft, a rod extending axially through the shaft, means for operatively connecting the rod to the rotatable burr, and a manually operable cam mounted on the base be- The spacing between the 5? neath the motorand engaging the rod for axially positioning the rod to regulate the clearance between the burrs.

2. In a device of the class-described, in combination, a vertically. mounted motor, a burr chamber constituting an integral part of the upper end. frame of the motor, an apertured removable cover for the chamber adaptedto be rigidly locked in closed position, a generally an nular, burrlfixedly supportedby the cover, a tubular armature shaft forthemotor, a-burr poopcrating with the fixed annular burr and slidable on and driven by the shaft, a cross member supporting the driven burr, a rod extending axially through the shaft and cooperating with the cross member to positionthe driven burr axially on the shaft, a cam assembly mounted on a base at the other end of the motor and engaging the rod for shifting the rod axially, and means for adjusting the position of the rod with respect to the cam assembly.

-3. In a coffee mill, in combination, a base, a motor mounted on end on the base, an upper end frame for the motor, said end frame including a cup-like portion serving as a grinding chamber, said motor having its armature shaft extended into the grinding chamber, a cover fitting the mouth of the grinding chamber, said cover having a central opening, an annular grinding burr fixed to said cover, a driven burr slidably mounted on the armature shaft, means extending through the armature'shaft for axially positioning the driven burr, said driven burr having a hub extending upwardly toward the opening in th annular burr, said hub and said armature shaft having alignable slots, a shear key fitted in the slots, and a feed screw fitted with a socket that fits over the ends of the hub and the armature shaft to retain the shearkey in place.

4. In a coffee mill, in combination, a motor that is mounted on end with its armature shaft vertical, an upper end frame for the motor, the end frame including an upwardly opening generally cylindrical cup-like portion serving as a grinding chamber, a cover for the grinding chamber, said cover having an opening for the introduction of material into the grinding chamber, a grinding burr fixed to the cover, a cooperating grinding burr mounted on the armature shaft of the motor, means extending through the armature shaft for adjusting the axial position of the cooperating burr to vary the spacing between the burrs, said cooperating burr having an upwardly directed hub, said hub and said armature shaft having aligned slots, a shear key in the slots, and a cap fitted over the end of the hub, said cap including a feed screw for drawing material into the grinding chamber.

5. In a coffee mill, in combination, a motor that is mounted on end with its armature shaft vertical, an upper end frame for the motor, a generally cylindrical grinding chamber formed in the upper end of said motor end frame, an apertured cover for the grinding chamber, a grinding burr fixed to the cover, a second grinding burr slidably carried on the armature shaft, means for positioning the second burr along the shaft, said second burr having an-upwar'dly extending hub, said hub and the armature shaft having slots, a shearable key in the slots, and a cap fitted over the hub and shaft to retain the shearable key in position in the slots.

GEORGE RUE WOOD.

(References on following page) 7 REFERENCES CITED The following references are of record in the" file of this patent:

UNITED STATES PATENTS 5 Number Name Date 82,362 SweSey Sept. 22, 1862 253,496 ROSS F6b.,14, 1882 359,587 WilCOX 81; a1 Mar. 15, 1887 375,533 Coles Dec. 27, 1887 10 1,344,453

Rousseau June 22, 1920 Number 8 Name Date Buckwalter May 1'7, 1927 Naul Mar. 27, 1928 Marsh June 3, 1930 Kopf et a1 Oct. 29, 1935 Meeker Sept. 28, 1937 Nable Nov. 29, 1938 Morgan Jan. 3, 19.39 Morehouse Feb. 21, 1939 Frock Aug. 29, 1939 Anderson Jan. 21, 1941 

